[LVI][CVP] LazyValueInfoImpl::solveBlockValueBinaryOp(): use no-wrap flags from add op

LebedevRI · LebedevRI · commit 1f665046fbf3 · 2019-10-23T18:17:32.000+03:00
Summary: This was suggested in https://reviews.llvm.org/D69277#1717210 In this form (this is what was suggested, right?), the results aren't staggering (especially since given LVI cross-block focus) this does catch some things (as per test-suite), but not too much: | statistic | old | new | delta | % change | | correlated-value-propagation.NumAddNSW | 4981 | 4982 | 1 | 0.0201% | | correlated-value-propagation.NumAddNW | 12125 | 12126 | 1 | 0.0082% | | correlated-value-propagation.NumCmps | 1199 | 1202 | 3 | 0.2502% | | correlated-value-propagation.NumDeadCases | 112 | 111 | -1 | -0.8929% | | correlated-value-propagation.NumMulNSW | 275 | 278 | 3 | 1.0909% | | correlated-value-propagation.NumMulNUW | 1323 | 1326 | 3 | 0.2268% | | correlated-value-propagation.NumMulNW | 1598 | 1604 | 6 | 0.3755% | | correlated-value-propagation.NumNSW | 7158 | 7167 | 9 | 0.1257% | | correlated-value-propagation.NumNUW | 13304 | 13310 | 6 | 0.0451% | | correlated-value-propagation.NumNW | 20462 | 20477 | 15 | 0.0733% | | correlated-value-propagation.NumOverflows | 4 | 7 | 3 | 75.0000% | | correlated-value-propagation.NumPhis | 15366 | 15381 | 15 | 0.0976% | | correlated-value-propagation.NumSExt | 6273 | 6277 | 4 | 0.0638% | | correlated-value-propagation.NumShlNSW | 1172 | 1171 | -1 | -0.0853% | | correlated-value-propagation.NumShlNUW | 2793 | 2794 | 1 | 0.0358% | | correlated-value-propagation.NumSubNSW | 730 | 736 | 6 | 0.8219% | | correlated-value-propagation.NumSubNUW | 2044 | 2046 | 2 | 0.0978% | | correlated-value-propagation.NumSubNW | 2774 | 2782 | 8 | 0.2884% | | instcount.NumAddInst | 277586 | 277569 | -17 | -0.0061% | | instcount.NumAndInst | 66056 | 66054 | -2 | -0.0030% | | instcount.NumBrInst | 709147 | 709146 | -1 | -0.0001% | | instcount.NumCallInst | 528579 | 528576 | -3 | -0.0006% | | instcount.NumExtractValueInst | 18307 | 18301 | -6 | -0.0328% | | instcount.NumOrInst | 102660 | 102665 | 5 | 0.0049% | | instcount.NumPHIInst | 318008 | 318007 | -1 | -0.0003% | | instcount.NumSelectInst | 46373 | 46370 | -3 | -0.0065% | | instcount.NumSExtInst | 79496 | 79488 | -8 | -0.0101% | | instcount.NumShlInst | 40654 | 40657 | 3 | 0.0074% | | instcount.NumTruncInst | 62251 | 62249 | -2 | -0.0032% | | instcount.NumZExtInst | 68211 | 68221 | 10 | 0.0147% | | instcount.TotalBlocks | 843910 | 843909 | -1 | -0.0001% | | instcount.TotalInsts | 7387448 | 7387423 | -25 | -0.0003% | Reviewers: nikic, reames Reviewed By: nikic Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D69321
diff --git a/llvm/include/llvm/IR/ConstantRange.h b/llvm/include/llvm/IR/ConstantRange.h
@@ -326,6 +326,14 @@ class LLVM_NODISCARD ConstantRange {
   ConstantRange binaryOp(Instruction::BinaryOps BinOp,
                          const ConstantRange &Other) const;
 
+  /// Return a new range representing the possible values resulting
+  /// from an application of the specified overflowing binary operator to a
+  /// left hand side of this range and a right hand side of \p Other given
+  /// the provided knowledge about lack of wrapping \p NoWrapKind.
+  ConstantRange overflowingBinaryOp(Instruction::BinaryOps BinOp,
+                                    const ConstantRange &Other,
+                                    unsigned NoWrapKind) const;
+
   /// Return a new range representing the possible values resulting
   /// from an addition of a value in this range and a value in \p Other.
   ConstantRange add(const ConstantRange &Other) const;
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1090,8 +1090,22 @@ bool LazyValueInfoImpl::solveBlockValueBinaryOp(ValueLatticeElement &BBLV,
     return true;
   }
 
-  return solveBlockValueBinaryOpImpl(BBLV, BO, BB,
-      [BO](const ConstantRange &CR1, const ConstantRange &CR2) {
+  if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(BO)) {
+    unsigned NoWrapKind = 0;
+    if (OBO->hasNoUnsignedWrap())
+      NoWrapKind |= OverflowingBinaryOperator::NoUnsignedWrap;
+    if (OBO->hasNoSignedWrap())
+      NoWrapKind |= OverflowingBinaryOperator::NoSignedWrap;
+
+    return solveBlockValueBinaryOpImpl(
+        BBLV, BO, BB,
+        [BO, NoWrapKind](const ConstantRange &CR1, const ConstantRange &CR2) {
+          return CR1.overflowingBinaryOp(BO->getOpcode(), CR2, NoWrapKind);
+        });
+  }
+
+  return solveBlockValueBinaryOpImpl(
+      BBLV, BO, BB, [BO](const ConstantRange &CR1, const ConstantRange &CR2) {
         return CR1.binaryOp(BO->getOpcode(), CR2);
       });
 }
diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
@@ -816,6 +816,21 @@ ConstantRange ConstantRange::binaryOp(Instruction::BinaryOps BinOp,
   }
 }
 
+ConstantRange ConstantRange::overflowingBinaryOp(Instruction::BinaryOps BinOp,
+                                                 const ConstantRange &Other,
+                                                 unsigned NoWrapKind) const {
+  assert(Instruction::isBinaryOp(BinOp) && "Binary operators only!");
+
+  switch (BinOp) {
+  case Instruction::Add:
+    return addWithNoWrap(Other, NoWrapKind);
+  default:
+    // Don't know about this Overflowing Binary Operation.
+    // Conservatively fallback to plain binop handling.
+    return binaryOp(BinOp, Other);
+  }
+}
+
 ConstantRange
 ConstantRange::add(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -289,11 +289,9 @@ define i1 @test8(i32 %a, i32 %b) {
 ; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw i32 [[A]], [[B]]
 ; CHECK-NEXT:    br label [[CONT:%.*]]
 ; CHECK:       cont:
-; CHECK-NEXT:    [[RES:%.*]] = icmp sge i32 [[ADD]], 0
 ; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
-; CHECK-NEXT:    [[IV:%.*]] = phi i1 [ true, [[BEGIN:%.*]] ], [ [[RES]], [[CONT]] ]
-; CHECK-NEXT:    ret i1 [[IV]]
+; CHECK-NEXT:    ret i1 true
 ;
 begin:
   %cmp0 = icmp sge i32 %a, 0
@@ -355,11 +353,9 @@ define i1 @test11(i32 %a, i32 %b) {
 ; CHECK-NEXT:    [[ADD:%.*]] = add nuw i32 [[A]], [[B:%.*]]
 ; CHECK-NEXT:    br label [[CONT:%.*]]
 ; CHECK:       cont:
-; CHECK-NEXT:    [[RES:%.*]] = icmp uge i32 [[ADD]], -256
 ; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
-; CHECK-NEXT:    [[IV:%.*]] = phi i1 [ true, [[BEGIN:%.*]] ], [ [[RES]], [[CONT]] ]
-; CHECK-NEXT:    ret i1 [[IV]]
+; CHECK-NEXT:    ret i1 true
 ;
 begin:
   %cmp = icmp uge i32 %a, 4294967040
